Comparison of Refractive and Visual Outcomes after Transepithelial Photorefractive Keratectomy (TransPRK) in Low versus Moderate Myopia

Is it possible to obtain good results in myopia of 2 or fewer diopters (D) with transepithelial photorefractive keratectomy (TransPRK) changing the optical zone and epithelium thickness? We retrospectively analyzed two groups of 296 eyes with a minimum follow-up of 4 months. Group A had 2 or less D, treated with an optical zone (OZ) 0.2 mm bigger than recommended, and a central epithelium thickness of 60 microns, and group B had 2 D to 5 D, with the recommended optical zone, and a 55-micron epithelium ablation at the center. The outcomes were not different between the two myopic ranges; the postop uncorrected distance visual acuity was 20/20 +/- 4 in both groups (p = 0.2), which was -0.3 +/- 0.8 lines worse than the preoperative corrected distance visual acuity in both groups (p = 0.5). The safety of the treatments resulted in a change of 0.0 +/- 0.7 lines in the low myopia group, versus a gain of +0.1 +/- 0.8 lines in the moderate myopia group (p = 0.1). The deviation from the intended target was -0.04 +/- 0.33 D in the low myopia group and +0.07 +/- 0.32 D in the moderate myopia group (p < 0.0001); the postoperative spherical equivalent was 0.00 +/- 0.33 D in the low myopia group and +0.10 +/- 0.31 D in the moderate myopia group (p < 0.0001). The postop refractive astigmatism was 0.32 +/- 0.16 D in both groups (p = 0.5). In conclusion, the refractive and visual outcomes after TransPRK are comparable in low myopia changing the optical zone and epithelium thickness versus moderate myopia with standard optical zone and epithelium thickness.